In the field of poultry farming, it is conventional to need to inject veterinary products, particularly vaccines, to the poultry.
The injections may be performed manually, However, in this case, a vaccination campaign proves to be excessively long. Furthermore, some injections need to be performed with satisfactory precision, as manual execution does not guarantee sufficient and/or consistent precision, particularly as an injection campaign frequently relates to a very large number of birds, implying considerable repetition of the actions of the operator (who needs to take hold of the fowl and perform the injection while holding the fowl firmly) and, consequently, tiredness of the operator liable to result in a lack of precision in the actions carried out.
Therefore, the prior art has proposed devices for assisting with the injection of veterinary products.
In particular, the patent document published under the number FR 2 276 838 is known, relating to a device for the automatic injection of a vaccine in the limb of a fowl comprising:                an injection syringe;        means for the retention of the animal to be treated, comprising abutment and gauge members formed by a removable fixed plate having a rectilinear edge and an oblique edge whereon the limb or neck of the bird or other part of the body is placed in a given transverse position and at a given angle in relation to the syringe;        means for advancing and retracting the syringe for each injection;        a control member such as a push button protruding slightly on the rectilinear edge of the plate such that the positioning of the animal activates the injection simultaneously.        
This technique involves a number of drawbacks including the following:                the retention means are devised to hold only one limb of the fowl, which limits the applications of the device (since many veterinary products need to be injected into other parts of the body of a fowl);        the means for holding the limb on the retention means are relatively basic and do not guarantee the presentation of limb of the fowl with a high level of precision;        the presence of a fowl and the injection is controlled by a type of push button; however, there is no guarantee that the fowl is positioned correctly at the time of injection;        the push button to be actuated by the positioning of the fowl may also be actuated inadvertently by the operator who may receive an injection, which obviously is to be avoided.        
Furthermore, the patent document published under the number FR 2 276 839 is known, relating to a device for vaccinating very small animals such as chicks, comprising                a syringe attached to the frame of the device and provided with a compressed air cylinder injection system;        two identical plates forming a groove having an angle of approximately 90° C. for receiving the necks of the chicks. The plates also comprise transverse hollows where the operators position their fingers and on either side of the neck of the chicks so as to hold same during the injection; and        a compressed air sensor, positioned behind one of the plates, which is blanked when an animal is positioned on the plates and thus controls the cylinder actuation mechanism.        
However, this device involves a number of drawbacks including the following:                it appears to be essentially suitable for the subcutaneous injection in the neck of small farmyard birds such as chicks and;        it only allows an approximate positioning of the birds on the device and does not offer any precision in relation to the contact area to be injected;        it likewise does not guarantee operator safety.        
According to a further technique described by the patent document published under the number U.S. Pat. No. 4,758,227, a vaccination device comprising a cradle retention member suitable for receiving the body of a fowl, in the vicinity whereof translatably movable injection means are mounted.
The device further comprises a member whereon the breast-bone of the bird is to be supported. This device is particularly suitable for injecting a vaccine into the breast-bone muscles of the bird, on each side. When the fowl is in position, the injection is activated by the operator, using a button or a control pedal.
This technique likewise involves the drawback of not enabling the precise positioning of the fowl in relation to the needles, with the injection thus possibly being carried out in an area of the body of the fowl which is ineffective or even inoperative or hazardous for the animal. Furthermore, the injection may be administered even if the position of the animal is not satisfactory.
Indeed, the injection of a veterinary product, particularly an intramuscular vaccine in the body of the bird must be performed precisely so as to avoid injecting organs or bones close to the target muscles. For example, in the case of the muscles adjacent to the breast-bone of a fowl, the injection must comply with all the following points:                the injection must not be too low on the body of the poultry, with a view to obligatorily avoiding an injection in the liver of the fowl (which would cause the death of the fowl almost instantaneously);        the depth of the injection must be perfectly controlled to prevent same being performed in the breast-bone (in which case, the injection would be ineffective or practically ineffective);        the injection must not be performed too high on the body of the fowl to avoid administering an injection of the clavicle of the poultry;        the injection must be administered with a predefined constant depth (in the region of 10 mm for hens of ten weeks and more).        
Furthermore, the injections must be performed such that the return of the syringes does not occur before the product has been injected entirely. In particular, in the case of the injection of two separate products, the difference in viscosity between the two products may require specific injection kinematics to enable the satisfactory diffusion of the products in the muscle.
In any case, the technique described by the document U.S. Pat. No. 4,758,227 cannot guarantee high-quality mass vaccination of poultry in terms of all the points cited above.
It is noted that the problem of poultry positioning precision is accentuated all the more as, generally, the operator performing the vaccination performs these actions at a high speed, on adult poultry that are difficult to handle, or if the areas to be injected are not readily visible for the operator.
A further technique described by the patent document published under the number U.S. Pat. No. 5,312,353 is known, relating to a device for vaccinating chicks. According to this technique, the device comprises a gauge comprising two surfaces at right angles, defining a space wherein the head and neck of a chick are to be introduced, each of the two surfaces having a sensor for detecting the presence of a chick, the simultaneous activation of both sensors activating vaccination.
Once again, this technique does not enable precise positioning of the poultry in the device and thus does not guarantee high-quality and/or consistent quality injection.
Furthermore, the positioning gauge has a very basic shape, inside which any part of a fowl could be introduced, while enabling the simultaneous actuation of both sensors, and thus the activation of vaccination.
According to a further technique described by the patent document published under the number FR 2 839 245, a poultry sanitary treatment station is proposed having a cradle comprising an area for receiving and supporting the breast of the fowl wherein an opening is formed to insert a syringe needle and incorporating a presence detector enabling, or not, the operation, by a separate control, of means for moving and actuating the syringe. Furthermore, the device comprises means for cutting the beak of the fowl.
The positioning of the fowl in the cradle is performed when the breast is present in the reception area and the beak of the fowl presented facing the corresponding cutting means.
It is noted that such as device only allows approximate positioning of the fowl in relation to the injection means.
In any case, this device does not guarantee injection quality as defined by the points listed above.